﻿using System;
using System.Linq;
using System.Collections.Generic;

namespace MartinRL.ProjectEuler
{
    /// <summary>
    /// http://projecteuler.net/index.php?section=problems&id=11
    /// </summary>
    public static class Problem011
    {
        public static int FindTheGreatestProductOfFourAdjacentNumbersInStringMatrix()
        {
            return new StringMatrix(adjacent: 4, stringMatrix:
@"08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48")
                .CalculateBiggestAdjacentProduct();
        }
    }
    
    public class StringMatrix
    {
        private readonly int adjacent;
        private readonly string stringMatrix;

        public StringMatrix(int adjacent, string stringMatrix)
        {
            this.adjacent = adjacent;
            this.stringMatrix = stringMatrix;
        }

        private int SideLength { get {return IntMatrix.Length.Sqrt();}}

        public int[,] IntMatrix
        {
            get { return stringMatrix.ToIntMatrix(); }
        }

        public int CalculateBiggestAdjacentProduct()
        {
            return HorizontalProducts
                    .Union(VerticalProducts)
                    .Union(Up45DiagonalProducts)
                    .Union(Down45DiagonalProducts)
                    .Max();
        }

        public IEnumerable<int> HorizontalProducts
        {
            get
            {
                for (var row = 0; row < SideLength; row++)
                    for (var col = adjacent - 1; col < SideLength; col++)
                        yield return CalculateHorizontalProductFor(col, row);
            }
        }

        public IEnumerable<int> VerticalProducts
        {
            get
            {
                for (var col = 0; col < SideLength; col++)
                    for (var row = adjacent - 1; row < SideLength; row++)
                        yield return CalculateVerticalProductFor(col, row);
            }
        }

        public IEnumerable<int> Down45DiagonalProducts
        {
            get
            {
                for (var row = 0; row < SideLength - (adjacent - 1); row++)
                    for (var col = 0; col < SideLength - (adjacent - 1); col++)
                        yield return CalculateDown45DiagonalProductFor(col, row);
            }
        }

        public IEnumerable<int> Up45DiagonalProducts
        {
            get
            {
                for (var row = (adjacent - 1); row < SideLength; row++)
                    for (var col = 0; col < SideLength - (adjacent - 1); col++)
                        yield return CalculateUp45DiagonalProductFor(col, row);
            }
        }

        private int CalculateUp45DiagonalProductFor(int col, int row)
        {
            return 0.To(adjacent - 1)
                .Select(t => IntMatrix[row - t, col + t])
                .Product();
        }

        private int CalculateDown45DiagonalProductFor(int col, int row)
        {
            return 0.To(adjacent - 1)
                .Select(t => IntMatrix[row + t, col + t])
                .Product();
        }

        private int CalculateVerticalProductFor(int col, int row)
        {
            return 0.To(adjacent - 1)
                .Select(t => IntMatrix[row - t, col])
                .Product();
        }

        private int CalculateHorizontalProductFor(int col, int row)
        {
            return 0.To(adjacent - 1)
                .Select(t => IntMatrix[row, col - t])
                .Product();
        }
    }

    public static class Problem011_Extensions
    {
        public static int[,] ToIntMatrix(this string @this)
        {
            // only supports square matrix as of now

            char[] delimiter = { '\n', '\r' };
            var rows = @this.Split(delimiter, StringSplitOptions.RemoveEmptyEntries);

            var length = rows[0].Split(' ').Length;
            var intMatrix = new int[length, length];

            for (var i = 0; i < length; i++)
            {
                var columnValues = rows[i].Split(' ');

                for (var j = 0; j < columnValues.Count(); j++)
                {
                    intMatrix[i, j] = columnValues[j].ParseAsInt();
                }
            }

            return intMatrix;
        }
    }
}